Download Midterm 2 Wednesday (Feb 29)

Midterm 2
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6:30PM Monday
DIFFERENT ROOM!!! Biochemistry 101
• (next building to East of BPS)
Exam format same as for Midterm 1
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Wednesday (Feb 29)
Review session
34 multiple choice questions
Sit in assigned rows
Bring photo ID
No calculators
Will cover material since midterm 1
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See course schedule (in syllabus on web site) for corresponding
textbook chapters.
But assumes you know the earlier material well enough to use it.
Will NOT include Pluto [9.3].
On the day of the midterm:
SIT IN YOUR ASSIGNED ROW!
TAKE ONLY THE TEST WITH YOUR NAME PRINTED ON THE FRONT COVER!
Seating Chart for Wednesday
Section 3, 10:20-11:10
SIT IN YOUR
ASSIGNED ROW!
(this seating chart is in the
Study Guide on Angel)
WHEN THE TESTS ARE
HANDED OUT,
TAKE ONLY THE
TEST WITH YOUR
NAME PRINTED ON
IT!
If your name falls in
alphabetical order
between the two
names listed for a row,
sit in that row.
Can’t figure it out?
PHOTO ID REQUIRED!
On exam day, a name-byname list will be posted
just inside the door.
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Midterm 2 – Wed. Feb.29
What to Know
• You should know about all of the things I have discussed in class since Midterm 1.
• This study guide just gives some of the high points.
• Study your lecture notes first, then use your textbook to help you understand your notes.
• Add pgs 333-336 “Star Birth” to the reading suggestions given in the syllabus.
• The test will only cover what I have discussed in class. This will NOT include Pluto
(textbook section [9.3]).
• There will be a number of questions about facts about the various planets, etc. What are their
surfaces and atmospheres like? How did they get that way?
• There are also a few more general ideas that you should understand, including the following
examples:
• What is the general layout of the solar system?
• Why does it have those properties? What does “angular momentum” (spin) have to do
with it?
• What led to the great difference between the terrestrial and the Jovian (Giant) planets?
• How do the processes of differentiation, tidal locking, and orbital resonances work?
• Age dating methods (radiactive decay, crater counting).
• Why is Venus so hot? Mars so cold?
• Some specific numbers to know (there are very few of these):
• Age of solar system. And how is it measured?
• Fraction of solar system’s mass that is in the Sun. Fraction of remaining mass that is in
Jupiter.
• Plus you should have an idea of relative sizes, distances, etc.
Overview of Solar System
• The solar system is a disk
• Rotation of sun, orbits of planets all in
same direction.
• Most planets rotate in this same sense.
(Venus, Uranus are exceptions).
• Angular momentum of pre-solar gas
cloud.
Object
Sun
Jupiter
Comets
All other planets
Satellites & rings
Asteroids
Cosmic dust
% Total Mass
99.8
0.1
0.05
0.04
0.00005
0.000002
0.0000001
• Terrestrial vs. Jovian (Giant) planets
• High vs. low density
• Rocks vs. mostly gas
• Composition
• heavy elements vs. primarily H/He
• Difference due to distance from Sun.
During planet formation in Solar Nebula:
Presence of ice
 more material for core
 could gravitationally attract large
masses of hydrogen & helium gas.
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• (Moon)
• Impact craters as clocks
• Old highlands (4.1-4.4 billion yrs)
• Heavily cratered
• Maria (3.3- 3.8 billion yrs)
• Fewer craters
• Rocks from each brought back by
Apollo astronauts.
• Age dating
• Chemical composition
• Tidally locked to Earth
• Formation of Moon
• Giant Impact is current favorite
theory… collision between Earth
& Mars-sized object.
Terrestrial Planets
• Earth
• Differentiated:
• Iron/nickel core
• Mantle of lighter rock
• Thin crust on top
• Evolution of atmosphere
• Thick CO2  life  N2, O2
• Current global warming
– Greenhouse effect
– Man-made CO2
Terrestrial Planets
• Mercury
• Closest to Sun, eccentric orbit.
• Airless, heavily cratered.
• Same density as Earth: iron-nickel
core.
• Geologically dead (probably)
• But cliffs  shrinkage at early
time.
• Rotates in 2/3 of its orbital period
• Tidal locking with a twist.
Mars
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(continued)
Venus
• Same size, density as Earth.
• Differentiated like Earth
• Surface mostly studied by radar
• Large volcanoes
• “Continents” pushed up by tectonic
flows in mantle.
• Recent lava flows, constant
resurfacing.
• Crater density  very young
surface
– only 750 million yrs old.
• Thick CO2 atmosphere
• Result of runaway greenhouse
effect.
• Keeps surface very hot (900F).
– Lead is molten.
• Retrograde (backward) rotation
• Probably due to giant impact.
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50% smaller diameter than Earth
1.5 times further from Sun.
Gigantic volcanoes.
50% highland “continents”
• Tharsis bulge.
• Cracked open to form Valles Marineris.
• 50% low-lying lava plains.
Atmosphere
• CO2, like Venus, but very thin.
• Liquid water currently impossible. Why?
Climate change
• Loss of atmosphere
• Low escape velocity
• Solar wind
• Could not retain heat
• Water froze out
• even less heat retained
• 2 Rovers found evidence of past water.
Life?
• Viking landers found no sign.
• Questionable data in meteorite.
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The Giant Planets
Jupiter – Saturn – Uranus - Neptune
• 14-300 x more massive than
Earth.
• Massive H + He atmospheres
• By far the most abundant
elements in the solar system.
• On top of rock/ice core
with 10-15 x mass of Earth.
• Lots of weather on Jupiter
• Ammonia (NH3) clouds.
• Strong winds at different
latitudes.
(differential rotation)
• Cyclonic storms
• Great Red Spot
– 2 x size of Earth
– 400 yrs so far
Earth
Some planets and moons (and Pluto)
shown in correct relative sizes
Planets:
orbit around
Sun
Dwarf Planets:
also orbit
Sun
Mars
Earth
Ganymede
Io
Venus
Titan
Moon
Moons:
orbit around
planets
Mercury
Europa
Callisto
Triton
Pluto
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Moons
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Jupiter’s Galilean moons, as we get closer to
Jupiter:
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Inner 3 galilean moons have ellipticalorbits due
to orbital resonances.
Jupiter’s 59 other moons are much smaller.
Saturn: over 30 known moons
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Callisto
Io
Callisto – ice, geologically dead.
Ganymede – ice, but geologically active.
Europa – rock, but covered by ice pack over
liquid water.
Io – rock, extreme volcanic activity.
Gradient of properties due to increased tidal
effects & heating from Jupiter.
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Jupiter
largest is Titan
• N2 atmosphere.
• Carbohydrate smog.
• Similar to Earth’s, but very cold (methane
lakes).
• Cassini/Huygens visit.
• See movie of Titan landing, on course
web site.
Enceledas
• much smaller than Titan.
• Has hot water down inside.
• Ejects ice and rocky material to form
Saturn’s E ring.
Europa
Ganymede
Rings
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All 4 giant planets have rings.
Jupiter, Uranus, Neptune have very thin rings.
Saturn has much larger rings.
Gravitational resonances important for shaping
details of rings
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Mimas created Cassini Division.
Shepherd satellites
• moons sweep out divisions, contain rings
through gravitational resonances.
Rings made of ice and small bits of dust.
Large moons cannot form inside of Roche
limit
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ripped apart because side of moon closer to
planet moves faster than side that is farther
from planet.
Roche limit ais at about 2.5x planet’s radius.
Asteroids
Comets
• Small rocky bodies in orbit about
sun.
• Mostly ice
• Some on highly eccentric orbits
• Left over from formation of
Solar System.
• Most, but not all, in asteroid belt.
• Some cross Earth’s orbit
Meteorites
• Asteroids that hit Earth and don’t
burn up in atmosphere.
• Analyzing them 
• Age of solar system (4.5 billion
yrs) How do we measure that?
• Initial chemical composition of
solar system.
• Spectacular tails when close to
Sun.
• Melted ice is driven off by solar
radiation, solar wind.
• Most come from Oort Comet
Cloud at edge of solar system.
• Some from Kuiper Belt, just
beyond Pluto.
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